Recently, display apparatuses used by a user wearing them at a head portion thereof, such as a head-mounted display, have been increasing. These display apparatuses form an image in front of a user's eyes, and thereby cause the user to view the image. As for these display apparatuses, there are a non-transmission type that covers a front portion of a user's eyes with a display unit and functions so as to prevent the user from viewing a reality space in front of the user's eyes; and a transmission type (optical see-through method) that has a display unit including a half mirror or the like and causes a user to view the reality space in front of the user's eyes.
For the non-transmission type of the display apparatus, for example, a displayed image can serve as an image in a virtual three-dimensional space generated by a game software.
Moreover, even as the non-transmission type of the display apparatus, there is an apparatus (referred to as a camera see-through method) simulatively realizing the transmission type of the display apparatus that displays a reality space, shot by a camera separately, in front of a user's eyes on a display unit and thereby causes the user to view the reality space in front of the user's eyes similar to the transmission type of the display apparatus.